Fastening device



June 29, 1943. H. KOCH 2,322,803

FASTENING DEVICE Filed Jan. 8, 1942 1 16.2. F1c3.3. F1 3,4.

WITNESSES: F l G 6 INVENTOR I 2 IGZSTAV H. KocH. QR-L5? 9mm ATTORNPatented June 29, 1943 FASTENING DEVICE Gustav H. Koch, Springfield,Mass, assignor to Westinghouse Electric & Manufacturing Company, EastPittsburgh, Pa., a corporation of Pennsylvania Application January 8,1942, Serial No. 425,957

9 Claims.

This invention relates to fastening means and more particularly to meansfor fastening sleeves to rotary shafts.

An object of this invention is to provide improved means for fasteningsleeves to rotary shafts.

Heretofore, sleeves have been fastened to rotary shafts by a set screwthat engaged a hole in the shaft or a fiat spot on the shaft. Due to therigidity of this structure it is hard to maintain a pressure between theshaft and the end of the set screw. The absence of such pressure resultsin rapidly increasing looseness and rattling of the sleeve on the shaft.Another objection to this type of connection is that sometimes thesleeve expands faster than the shaft. The result of this is a loose andnoisy connection. Accordingly, it is an object of this invention toprovide means for attaching a sleeve to a shaft that eliminates theseobjections.

Another object is to provide means for fastening sleeves to rotaryshafts wherein a resilient pressure is maintained between the sleeve andthe shaft.

A further object is to provide means for attaching sleeves to rotaryshafts which provides a positive connection having substantiallynoiseless operational characteristics.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawing. forming a part of this application, inwhich:

Fig. 1 is a side view of a fan illustrating one application of thisinvention;

Fig. 2 is an enlarged partial section showing the relation of parts ofthe fastening means just prior to the completion of the final operationnecessary to fasten a sleeve to a shaft;

Fig. 3 is an enlarged partial section showing the relation of parts ofthe fastening means when fastening a sleeve to a shaft;

Fig. 4 is a section taken along the line IVIV of Figs. 1 and 2;

Fig. 5 is a section through the shaft alone as seen along line IVIV ofFig. 2 and,

Fig. 6 illustrates how this invention may be applied to connect twoshafts.

Referring to the drawing in detail, Fig. 1 shows a fan I0 illustratingone application of this invention. The fan I 0 includes a support II, amotor I2, a shaft I3 rotated'by the motor I2, a set of fan blades I4which are attached to a sleeve I5. A novel arrangement is provided forfastening the sleeve 15 to the rotary shaft I3 so that the fan bladeswill rotate therewith.

The fastening arrangement includes a stepped notch which is provided bya first notch I1 and a second notch I8 in the shaft IS, a pair ofnotches I9 in the sleeve I5, a set screw 2|] screwthreaded into thesleeve I5, and a flat resilient spring key 2|.

The notch I8 is located in the bottom of and intermediate the ends ofthe notch N. This arrangement of the notches I1 and I8 provides flatlands 22 between the ends of the notches. These notches may be milledinto the shaft I3 with a single operation using a stepped milling toolor they may be formed therein by two separate milling operations usintwo different width milling tools. The notches I9 in the sleeve I5complement the notches I! and I8 in the shaft I3. These notches may beformed in the sleeve I5 by means of a broach or any other suitablemeans. The notches I1 and I8 have flat bottoms and when assembling thefastening means, the key 2| is placed in the slot IT with its ends 24resting on the flat lands 22 as shown in Fig. 2 and the sleeve I5 isslid onto the shaft and the set screw 20 is tightened down against thespring key 2| so as to force the central portion 23 of the key 2I downinto the notch I8 as shown in Fig. 3. The portion 23 may or may not beforced down against the flat bottom of the notch I8 depending upon thedegree of resiliency desired in the connection. As the set screw 20 istightened down onto the key, the ends 24 of the key pivot about corners25 between the slots I1 and I8 and bear against the top wall of thenotches IS. The contact between the key and the notches I9 is over foursmall areas, indicated generally by the reference character 28. Thisarea contact is obtained by the ends of the key flattening out againstthe top walls ofthe notches I9 when the set screw 20 is screwed downtight against the key,

The spring key 2| engages the shaft along a line transverse to the shaftat the corners 25 and along a line transverse to the shaft at 2'! andthe ends of the same, as previously described, engage the sleeve I 5over the small areas indicated at 28. This arrangement maintains aresilient pressure against both the threads of the screw 20 and theshaft I3 which tends to prevent loosening of both the screw 2|] and theshaft I3. This arrangement also provides a much greater radial pressurebetween the sleeve I5 and the shaft l3 than can be applied with a setscrew seating in a hole in the shaft or on a flat spot on the shaft l3because the spring key 2| pivots about the corners 25 as fulcrum pointsand acts on the well-known principle of the lever to multiply thereaction of the screw 20. It will be noted that the distance from thefulcrum points or corners 25 to the line 21 is greater than the distancefrom the fulcrum points 25 to the ends 24 of the spring key.Accordingly, since the structure is in equilibrium, the reaction of thespring key 2| on the sleeve over the areas 28 must necessarily be morethan one-half the reaction of the screw on the spring key 21, andthe-reaction at each of the fulcrum points 25 is equal to one-half thereaction of the screw 20 on the key 2| plus the reaction at the twocontact areas 28 at each end of the key Zli.

Another advantage afforded by this invention is that it provides aplurality of points of positive pressure between the sleeve I5 and theshaft 13. This provides a very stable connection, that is, free fromboth rotation and wobble.

Still another advantage is that, due to the resiliency of the spring key2|, if the sleeve I 5 expands quicker than the shaft l3, the connectionbetween them will remain tight and substantially noiseless.

Fig. 6 illustrates another use for the fastening arrangement justdescribed. In this application of the invention, two aligned shafts 30and 3| .are connected together.

have notches I1 and I8 formed therein near their respective adjacentends, and a flat resilient spring key 2 l is positioned in each of thenotches H. A sleeve 32 is telescoped over the adjacent ends of theshafts '30 and 3|. pair of notches l9 therein, similar to the notches I9in the sleeve I5 of the previous embodiment, that complements thenotches l1 and IS in the shafts. A pair of set screws 20 are threadedinto the sleeve. The set screws 20' are located opposite the spring keys2 l so that when are screwed down onto the keys 2| the shafts .arefastened "to the sleeve, and consequently together, in the mannerpreviously described for fastening the sleeve 55 to the shaft l3.

While I have shown my invention in several forms, it will be obvious tothose skilled in "the art that it is not so limited, but issusceptibleof various other changes and modifications without departing from thespirit thereof, and I desire, therefore, that only such limitationsshall be placed thereupon as are specifically set forth in the appendedclaims.

What I claim is:

-1. A ,rotary shaft having a notch therein, a sleeve mounted on saidshaft, means fastening said sleeve to said shaft so as to rotatetherewith, said means including an initially fiat spring key in saidnotch, and a device carried by said sleeve for applying a force to saidspring key to deflect a portion thereof into engagement with said shaftand other portions thereof into engagement with said sleeve.

2. A rotary shaft having first and second notches therein, said second,notch being located Each of the shafts This sleeve has a within theconfines of said first notch, a sleeve mounted on said shaft, a springkey positioned in said first notch, means carried by said sleeve forapplying force to said spring key to force a portion of said spring keyinto said second notch and cause the same to engage said shaft and saidsleeve at a plurality of points.

3. A rotary shaft having a notch therein, a sleeve mounted on saidshaft, a spring key positioned in said notch, means carried by saidsleeve for applying pressure to said spring key intermediate its ends,and fulcrum points intermediate the ends of said notch about which theends .of said spring key pivot into contact with said sleeve whenpressure is applied to said key.

4. A rotary shaft having first and second notches, therein, a sleevemounted on said shaft, said sleeve having a notch therein complementingsaid first notch in said shaft, a spring key positioned in said firstnotch-in said shaft, means tions of said spring key to apply a resilientforce to said shaft and to said sleeve at a plurality of points.

6. A rotary shaft having a shallow notch therein, a sleeve mounted onsaid shaft, an initially fiat spring key positioned in said notch, andmeans for causing said spring key to engage said shaft at at least twopoints and to engage said sleeve at at least two points.

'7. A rotary shaft having a shallow notch therein, an initially flatspring key positioned in said notch, a sleeve mounted on said shaft,means for causing said spring key to apply a resilient force to saidsleeve at at least three points and to apply a resilient force to saidshaft at at least two points. I

8. A rotary shaft having a stepped notch therein, a spring keypositioned in said notch and resting on the steps of the same, a sleevemounted on said shaft, and means applying a force to said spring keythat causes a portion of said key to engage the bottom of said notch andthe ends of said key to engage said sleeve.

9. Fastening means for securing a sleeve to a rotatable shaft so as torotate with said shaft comprising a key positioned in a recess formedbetween a portion of said sleeve and a portion of said shaft, fulcrumpoints bearing against said key at points intermediate the center andend portions thereof and means for exerting pressure on the centerportion of said key for causing the intermediate-and the end portions ofsaid key to press against the adjacent portions of said shaft and saidsleeve.

GUSTAV H. KOCH.

